Musicians have played stringed instruments for millennia. The lute and the lyre have been known for at least four thousand years. Despite this longevity, significant innovation in the apparatus and techniques of stringed instrument technology continues to be made. If anything, the pace of such change is increasing, such that much of the music now produced with stringed instruments would have been completely alien to the musicians and composers of only a century ago. The opportunity clearly exists for significant further innovation.
Stringed instruments include an elongate elastic member, or string, disposed in tension between respective pairs of fixed string ends. Energy is stored in the string by, for example, bowing, hammering or plucking the string. The stored energy is then released by oscillatory motion of the string. The release of energy takes place both directly to surrounding air displaced by the moving string, and indirectly as the momentum of the string is transferred to a soundboard through a bridge. Often a resonant chamber is attached to the soundboard. The structure of the resonant chamber, and the air therewithin, oscillates in resonance with the vibrating string to produce relatively louder tones and various harmonics.
In other stringed instruments, a sensor, called a pickup, detects the motion of the string with respect to the pickup. This detection may include sensing a perturbation in a magnetic or electric field related to string motion. Typically, the pickup produces an electrical output signal related to the oscillatory motion of the string. The electrical signal is usually amplified by a system including an active electronic component, such as a transistor or a vacuum tube, to produce an amplified electronic signal. The amplified electronic signal may, in turn, be used to control an output transducer that produces audible signals in a surrounding medium, most commonly air. Common examples of output transducers include speakers and headphones. The amplified electronic signal may also be used to control an analog or digital recording device, such as a magnetic tape system so that the oscillatory pattern produced by the string may be reproduced at a later time.
The oscillatory motion of a string depends on such factors as the length of the string, the weight of the string, its diameter, it elasticity, and the tension under which it is placed. Additional factors include the characteristics of the medium surrounding the string, and the mechanisms by which the ends of the string are secured. Also significant are the structure and characteristics of any bridge, soundboard, pickup, etc. with which the string interfaces. During operation of an instrument these characteristics and factors may be substantially invariant, or may vary in intended and unintended ways. In particular, many stringed instruments are controlled by varying effective string length and tension and by manipulation of one or more strings.
Many instruments, such as the lute, the guitar, the violin, the viola, and the string base include a fingerboard. The fingerboard is typically made of wood and includes an elongate upper surface above which a plurality of strings is stretched taught. Some instruments have a plurality of frets disposed on the upper surface of the fingerboard in substantially perpendicular relation to the taught strings. An individual playing such an instrument activates one or more of the strings using one hand, and uses the digits of a second hand to urge selected strings towards the fingerboard. The string comes in contact with one of the frets and/or the fingerboard, and this point of contact defines an effective length of the string with respect to the second end. The effective length of the string is dynamically varied by moving the fingers of the second hand to produce varying tones as music is played. Depending on the skill of the player and the characteristics of the instrument, highly complex and rapidly varying combinations of tones may be produced.
Musicians have a variety of techniques for applying the fingers of the second hand to the strings and urging the strings towards the finger board. In some of these techniques, pressure is applied to a rear surface of the neck of the instrument using a thumb of the second hand. The pressure applied by the thumb operates in a direction opposite to that applied by the fingers so that the strings and neck of the instrument are pinched together between thumb and fingers. As the instrument is played, the second hand is moved longitudinally up and down the neck of the instrument while the aforementioned forces are serially applied and released. During this motion, the thumb may remain in contact with the rear surface of the neck, sliding across that surface and aiding in the rapid and precise positioning of the second hand.
Activating a string produces a note. A musical chord is produced when a plurality of strings of an instrument are activated at a particular time to produce a corresponding plurality of notes. The chord is the combination of notes resulting when the plurality of notes are played together.
The characteristics of music produced by the player of such an instrument are limited by the player's ability to apply and release his or her fingers in relation to the strings and fingerboard. In particular, the maximum distance, or span, between a player's extended fingers limits the respective points at which multiple strings may be simultaneously depressed, and hence limits the chords and sequences of notes that may be produced.
It is known in the art to apply a device called a capodastro or capo, to an instrument in order to modify the effective length of one or more strings of the instrument without applying finger pressure to those strings (i.e. when the strings are open). Generally speaking, a capo includes a detent device that temporarily urges the strings towards the fingerboard, so that an effective length of the string is defined by a pinch point between the capo and the fingerboard, or at a fret over which the string is drawn, by application of the capo.
U.S. Pat. No. 468,193 to Dahlman et al. (the disclosure of which is herewith incorporated by reference in its entirety) describes a capo for application to stringed instruments such as guitars, violins, etc. The Dahlman capo includes a plate with a cushion at its underside, the cushion being adapted to engage the strings of an instrument, and depress the strings firmly in place on top of the neck so as to raise the tone of the instrument. The plate extends transversely across the neck of the instrument and has at its middle a lug, pivotally connected to a yoke that extends transversely on one side of the neck to reach with a lower arm under the neck. The lower arm has a cushion that pivotally engages an underside of the neck such that the strings are clamped in place on the neck. This clamping is effected by a V-shaped spring connected with a hand lever.
U.S. Pat. No. 5,117,723 to Venschoten (the disclosure of which is herewith incorporated by reference in its entirety) shows a further capo having a cushioned top pressure bar adapted to engage the strings of an instrument, and a brace or lever adapted to pivotally engage the neck of the instrument. According to Venschoten this pivotal engagement is effected by a worm gear arrangement.
U.S. Pat. No. 6,573,440 to Rodriguez and U.S. Pat. No. 6,528,711 to Paige (the disclosures of which are herewith incorporated by reference in their entirety) show respective capos in which clamping is effected by the compression and torsion of a coil spring respectively.
Various prior art capos have the capacity to clamp particular strings of an instrument selectively, without simultaneously contacting all strings of the instrument. Such capos are shown in U.S. Pat. No. 3,011,380 to Brimhall, U.S. Pat. No. 3,680,427 to Valentino, U.S. Pat. No. 4,183,279 to Shabram Jr., U.S. Pat. No. 4,334,457 to Spoonts III U.S. Pat. No. 5,623,110 to Hogland et al. and U.S. Pat. No. 6,521,820 to Patel. Each of these is herewith incorporated by reference in its entirety. As in the foregoing references, each of these references shows a capo in which a member applied to a rear surface of an instrument neck urges a further member, and therefore a string of the instrument against an opposite face of the instrument neck.
In the case of the Patel and Hogland references, the respective capo is applied by pivotally actuating a pair of handles that protrude away from the instrument neck in substantially perpendicular relation to the longitudinal axis of the neck.
In use, the protruding handles of the Patel and Hogland capos may interfere with the motion, with respect to the instrument neck, of the musician's second hand. This interference may make the playing of some notes and chords difficult or impossible. It may also reduce the rapidity with which playable notes and chords may be produced.
Similar interference may also result in the case of other prior art capos where, for example, a retaining bar or strap extends transversely across the rear surface of the instrument neck. In view of these and other limitations, it is believed that an opportunity exists to advance the state-of-the-art.